2,851 research outputs found

    Global and Regional IUCN Red List Assessments: 10

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    In this contribution, the conservation status assessment of two vascular plants according to IUCN categories and criteria is presented. It includes the regional assessment of Jasione orbiculata Griseb. ex Velen. for Italy and of Vachellia gerrardii (Benth.) P.J.H.Hurter subsp. negevensis (Zohary) Ragup., Seigler, Ebinger & Maslin for Iraq

    Partitioning of Dry Matter into Fruit Explains Cultivar Differences in Vigor in Young Olive (Olea europaea L.) Trees

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    Low vigor and early and abundant production are desirable traits for modern tree crops. In olive, most cultivars are too vigorous and cannot be successfully constrained in the small volume allowed by the straddle harvester used in the so-called superhigh-density (SHD) orchards. Only few cultivars appear to have sufficiently low vigor to be suitable for this system. These cultivars combine low vigor with earlier and higher yield. This study investigated the hypothesis that differences in vigor between Arbequina, a low vigor and the most commonly used cultivar in SHD orchards, and Frantoio, a highly vigorous cultivar not suitable for such orchards, are related to their differences in early bearing and consequent differences in dry matter partitioning into fruit. Young trees of both cultivars were deflowered either in 2014, 2015, both years, or neither one, resulting in a range of cumulative yields over the 2 years. Tree trunk cross-sectional area (TCSA) was measured at the beginning of each year. This was closely related to total tree mass, as assessed at the beginning and at the end of the experiment. Cumulative yield, in terms of fruit dry matter, was also assessed. TCSA increased less in fruiting trees in both years. As expected, when not deflowered, 'Frantoio' was less productive and more vigorous than 'Arbequina'. However, there was no difference in TCSA increment when both cultivars were completely deflowered. TCSA increments were closely inversely related to yield across all treatments and cultivars (R2 = 0.90). The regressions improved further when data from 2015 only were used (R2 = 0.99). The results represent the first quantitative report showing that differences in vigor among cultivars can be completely explained in terms of different dry matter partitioning into fruit, supporting the hypothesis that early bearing is a major cause, rather than merely a consequence, of lower vigor in young 'Arbequina' trees. These results provide new understanding on vigor differences across cultivars, which will be useful for breeding and selection of new genotypes

    Centrality dependence of pi(+/-), K-+/-, p, and (p)over-bar production from root(NN)-N-S = 130 GeV Au+Au collisions at RHIC

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    Identified pi(+/-), K+/-, p, and (p) over bar transverse momentum spectra at midrapidity in root s(NN) = 130 GeV Au + Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. Within errors, all midrapidity particle yields per participant are found to be increasing with the number of participating nucleons. There is an indication that K+/-, p, and (p) over bar yields per participant increase faster than the pi(+/-) yields. In central collisions at high transverse momenta (p(T) greater than or similar to 2 GeV/c), (p) over bar and p yields are comparable to the pi(+/-) yields

    Net charge fluctuations in Au+Au interactions root s(NN)=130 GeV

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    Data from Au+Au interactions at s(NN)=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays

    Measurement of single electrons and implications for charm production in Au+Au collisions at root(NN)-N-S=130 GeV

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    Transverse momentum spectra of electrons from Au+Au collisions at roots(NN) = 130 GeV have been measured at midrapidity by the PHENIX experiment at the Relativistic Heavy Ion Collider. The spectra show an excess above the background from photon conversions and light hadron decays. The electron signal is consistent with that expected from semileptonic decays of charm. The yield of the electron signal dN(e)/dy for p(T) \u3e 0.8 GeV/c is 0.025 +/- 0.004(stat) +/- 0.010( syst) in central collisions, and the corresponding charm cross section is 380 +/- 60(stat) +/- 200(syst ) mu b per binary nucleon-nucleon collision

    Suppression of hadrons with large transverse momentum in central Au+Au collisions at root s(NN)=130 GeV

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    Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 Gev/c \u3c P - T \u3c 5 GeV/c have been measured by the PHENIX experiment at RHIC in Au + Au collisions at root S(NN) = 130 GeV. At high p(T) the spectra from peripheral nuclear collisions are consistent with scaling the spectra from p + p collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled p + p expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies

    Event-by-event fluctuations in mean p(T) and mean e(T) in root s(NN)=130 GeV Au+Au collisions

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    Distributions of event-by-event fluctuations of the mean transverse momentum and mean transverse energy near mid-rapidity have been measured in Au+Au collisions at roots(NN)=130 GeV at the Relativistic Heavy-Ion Collider. By comparing the distributions to what is expected for statistically independent particle emission, the magnitude of nonstatistical fluctuations in mean transverse momentum is determined to be consistent with zero. Also, no significant nonrandom fluctuations in mean transverse energy are observed. By constructing a fluctuation model with two event classes that preserve the mean and variance of the semi-inclusive p(T) or e(T) spectra, we exclude a region of fluctuations in root s(NN)=130 GeV Au+Au collisions

    Transverse-mass dependence of two-pion correlations in Au+Au collisions at root(NN)-N-S=130 GeV

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    Two-pion correlations in roots(NN) = 130 GeV Au+Au collisions at RHIC have been measured over a broad range of pair transverse momentum k(T) by the PHENIX experiment at RHIC. The k(T) dependent transverse radii are similar to results from heavy-ion collisions at roots(NN) = 4.1 , 4.9, and 17.3 GeV, whereas the longitudinal radius increases monotonically with beam energy. The ratio of the outwards to sidewards transverse radii (R-out/R-side) is consistent with unity and independent of k(T)

    Measurement of the midrapidity transverse energy distribution from root(NN)-N-S=130 GeV Au+Au collisions at RHIC

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    The first measurement of energy produced transverse to the beam direction at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is presented. The midrapidity transverse energy density per participating nucleon rises steadily with the number of participants, closely paralleling the rise in charged-particle density, such that ⟨ET⟩/⟨Nch⟩ remains relatively constant as a function of centrality. The energy density calculated via Bjorken’s prescription for the 2% most central Au+Au collisions at √sNN=130GeV is at least εBj=4.6 GeV/fm3, which is a factor of 1.6 larger than found at √sNN=17.2 GeV ( Pb+Pb at CERN)
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